Photographic processing apparatus

ABSTRACT

Apparatus for applying an accurately predetermined quantity of a liquid processing agent uniformly to successive exposed areas of photosensitive sheet material. The apparatus includes an applicator roll with a grooved surface rotated in a liquidcontaining well and the sheet material is moved upwardly at an angle in contact with the oppositely moving surface of the roll to form a meniscus of the liquid between the roll surface and the sheet material. One side of the well is higher than the other and includes a cylindrical surface cooperating with the roll surface to form a throat for controlling the quantity of liquid carried upwardly by the roll through the throat into contact with the sheet.

United States Patent [72} lnventor Nicholas Gold Arlington, Mass.

[211 App]. No. 723,040

[22] Filed Apr. 22, 1968 [45] Patented Jan. 5, 1971 [73] AssigneePolaroid Corporation Cambridge, Mass. a corporation of Delaware [54]PHOTOGRAPHIC PROCESSING APPARATUS 3,301,156 l/l967 Roeber 95/89 F ORElGNPATENTS 1,036,839 7/1966 Great Britain i 18/246 Primary ExaminerJohn M.Horan Assistant Examiner-Robert P. Greiner Attorneys Brown and Mikulkaand Robert E. Curb ABSTRACT: Apparatus for applying an accuratelypredetermined quantity of a liquid processing agent unifonnly tosuccessive exposed areas of photosensitive sheet material. The apparatusincludes an applicator roll with a grooved surface rotated in aliquid-containing well and the sheet material is moved upwardly at anangle in contact with the oppositely moving surface of the roll to forma meniscus of the liquid between the roll surface and the sheetmaterial. One side of the well is higher than the other and includes acylindrical surface cooperating with the roll surface to form a throatfor controlling the quantity of liquid carried upwardly by the rollthrough the throat into contact with the sheet.

PATENTED JAN 5 m1 SHEET 1 OF 2 INVENTOR. M04024 "50% 252mm and W and W6'. $97K- ATTORNEYS PATENTED JAN SIS?! 3552.292

saw 2 or 2 INVENTOR.

filww namdmala and EM 5. 6% ATTORNEYS PHOTOGRAPHIC PROCESSING APPARATUSThe present invention is concerned with a liquid applicator especiallydesigned to apply an accurately predetermined quantity of a processingliquid to sheet material and is particularly adapted for incorporationin hotographic apparatus such as document copiers wherein an aqueousprocessing liquid is applied to successive exposed areas ofphotosensitive sheet material to form visible images therein. lndocument copying apparatus of this type successive areas of sheetmaterial including, for example, a layer containing a photosensitiveimage-recording medium such as silver-halide, are exposed and thenadvanced as individual sheets through the applicator which is requiredto apply a predetermined quantity of a processing liquid uniformly tothe entire exposed area or sheet while the latter is moved at acomparatively rapid linear rate relative to the applicator. in typicalapparatus of this type, the exposed area or sheet is rectangular andmeasures 8% X ll inches and the applicator is required to apply theliquid commencing with leading edge of the sheet so as to coat theentire sheet completely and uniformly with a very precisely meteredquantity of the liquid.

In a typical photographic process adapted to be performed by theapplicator apparatus of the invention, a composite photosensitive sheetincluding a support such as paper and at least a layer containing aphotosensitive material such as silver-halide, a white opacifying agentand an agent providing a silver precipitating environment, is exposed toproduce a latent image in the sheet and is thereafter treated with anaqueous alkaline liquid processing solution to produce a visible imageby a diffusion transfer reversal process. The processing solution mayinclude, among other constituents, a silver-halide developer and asilver-halide complexing agent which may be present initially in thesolution applied to the sheet or may be included in a dry form in thesheet itself in which case the processing liquid will be so constitutedto activatethe agents in the sheet and will include water and an alkali.The processing liquid is applied to one sideof the sheet and isimmediately absorbed thereby initiating processing in which exposedsilver-halide is developed and an imagewise distribution of diffusibleimage-forming substances such as a soluble silver complex, is formedfrom unexposed silver-halide and is transferred by diffusion to a layeror a strata providing a receptive environment for the image-formingsubstances, for example, a silver precipitating environment in whichsilver is precipitated from the complex to form a positive image. Fordetails of process of this type and materials employed therein referencemay be had to the copending US. Pat. application of Edwin H. Land et al.Ser. No. 519,884, filed Jan. 11, 1966, now US. Pat. No. 3,507,650.

Image-forming processes of the type described occur very rapidly, e.g.in a few seconds, so that it will be apparent that in a process of theforegoing type, a number of different but closely related reactionsoccur at the same or nearly the same time; and that the quantity ofliquid applied to the sheet material-and available for processing iscritical, insufficient liquid may upset the rate relationships betweenthe various processes and/or prevent the image-forming process fromcontinuing to completion; while excess processing liquid may also have adisturbing effect upon the process relationships and provides areservoir in the sheet of excess processing a liquid which maycontribute to undesirable diffusion of the image-formin g substances orcause the transfer image to be washed" away and which must be removedfrom the sheet material constituting the finished print or copy. Notonly is the quantity of the liquid applied critical to properimage-formation, but it is relatively small and it must be applieduniformly to only one side of the sheet while the sheet is in motion.For example, in a typical process such as described in theaforementioned Land et al. application, approximately 0.7 to 0.8 cc ofthe processing liquid is all that is required to be applied to an areaof the sheet material measuring 8 /2 X ll inches, or

, enough to form a layer on this area .0006 inch deep while the sheet ismoved relative to the processor at linear speeds ranging from 3 to l0inches per second.

Objects of the invention are: to provide photographic processingapparatus of the type described adapted to apply rapidly and uniformly,accurately predetermined and relatively small quantities of a nonviscousphotographic processing liquid to one side of each of successive areasof photosensitive sheet material; to provide liquid applicator apparatusof the type described including a roll rotated in a liquid-containingwell having a wall cooperating with the roll to control the quantity ofliquid applied to the sheet material; and to provide liquid applicatorapparatus as described which is dependable and reliable in its operationwhile having a simple and inexpensive instruction.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the apparatus possessing theconstruction, combination of elements and arrangement of parts which areexemplified in the following detailed disclosure, and the scope of theapplication of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawings wherein:

FIG. 1 is a perspective view, partially in section with parts brokenaway, showing a liquid applicator embodying the invention;

FIG. 2 is a sectional view through the applicator of FIG. 1;

FIG. 3 is an enlarged, fragmentary, perspective view of the roller ofthe applicator; and

FIG. 4 is an enlarged, fragmentary, sectional view illustrating theoperation of the applicator.

The liquid applicator ofthe invention is specially designed forincorporation in document copying apparatus adapted to be employed withan integral image-recording and imagereceiving sheet material and toperform a process of the type described in the aforementioned Land etal. patent application. The sheet material comprises a paper supportcarrying on one side at least a layer including a stratum containing alight-sensitive silver-halide emulsion and an outer stratum comprising atranslucent material such as finely divided titanium dioxide dispersedin a suitable permeable colloidal carrier on matrix such as gelatinwhich is permeable to an aqueous processing liquid. The translucentpigment may be incorporated in the stratum containing thelight-sensitive material and/or may comprise a separate outer stratumwhich also contains silver precipitating nuclei providing asilver-receptive stratum. The outer stratum is sufficiently lighttransmitting to permit exposure of the light-sensitive material therebeneath while at the same time being sufficiently opaque to provide arequisite background for a positive silver image transferred thereto bydiffusion and to mask a negative image formed thereunder. Processing ofthis exposed integral image-recording and image-receiving sheet isaccomplished with an aqueous alkaline liquid including a silver-halidedeveloper such as phynelhydroquinone and a silver-halide complexingagent such as sodium thiosulfate, which is applied to the coated side ofthe sheet opposite the support so as to impregnate the lightsensitivestratum with sufficient processing liquid to produce a positive silvertransfer image on the surface of the translucent layer. In a preferredprocess the silver-halide developer is incorporated, in a dry orcrystalline form, in the strata containing the silver-halide emulsion,and the processing liquid constitutes an activator solution, theprincipal ingredients of which are water, alkali, and the silver-halidecomplexing agent. This latter composition is preferred to including thedeveloper in the processing liquid because it reduces the problemsattendant to storing the liquid so as to prevent oxidation of thedeveloper. However, the liquid is extremely alkaline having a pH of theorder of 13 to 14 so that the problems of storing, handling, andapplying a highly caustic and corrosive liquid remain.

Reference is now made to H08. 1 through 3 of the drawings wherein thereis illustrated a liquid applicator designated 10 including a body 12, aroll 14 and a cover 16L Body"l is formed with an elongated well 18extending substantially from end to end of the body and having a lengthat leastequal to the width of the sheet material to becoated. Roll 14 iscylindrical, has a length at least equal to the width of the'area of thesheet material to be coated and is mounted for rotation about its axiswithin the well. Body 12 includes end walls 20 and roll 14 is mountedfor rotation on shafts 22 journaled in end walls 20, the latterpreferably being provided with liquidtight seals around shafts 22 toprevent liquid within the well from leaking around the shafts. Theapplicator is designed to be employed while oriented so that the axis ofroll l4.lies in a substantially horizontal plane and will be describedas being so oriented.

Body 12 includes a longitudinal section 24 extending upwardly above roll14 and having an inner cylindrical surface 26 defining one sidewall ofwell 18 extending from beneath roll 14 upwardly parallel with theperipheral surface of the roll to a position at least above a horizontalplane through the axis of the roll and preferably to a position as shownabove the roll axis. inner surface 26 is bounded by a lower edge locatedbeneath the roll approximately in line with the roll axis and is spacedfrom the roll surface so as to cooperate therewith to define a narrowthroat 28 commencing at the lowest part of the roll surface and adaptedto perform a function which will be described in greater detailhereinafter. Body 12 includes another side section 28 defining theopposite side of well!!! which is also provided with a sump 30 forcollecting any residue of materials which may 'wash off the sheetmaterial during application of liquid thereto. 1

The upper surface of side sections 24 and 28 are adapted to providemeans for supporting and guiding sheet material to be coated upwardlyand at an angle (from right to left viewing F IGS. 2 and 4) across andin contact with a descending portion of the roll surface. These supportsurfacesdesignated 32 and 34 are located in the same plane disposed atapproximately a 45 angle with respect to the horizontal when theapplicator is operatively positioned, i.e., with the axis of rbll l4lying in a horizontal plane, and the peripheral surface of toll 14projects from well 18 beyond the plane of surfaces 32 and 34 so as tocontact a sheet guided along and supported o the support surface.

Cover 16 is pivotally mounted at its ends on shafts 36 engaged' inopenings 38 in extensions40 of sidewalls'20 of body 12 and is positionedin covering relation to the roll mounted in well 18. Cover 16 includes alongitudinal recess 42 approximately equal in length to the length ofthe well and upper and lower edge sections 44 and 46 having surfacesadapted to engage support surfaces 32 and 34, respectively, in theclosed position of the cover. Cover 16 is 'pivotable about shafts '36between the closed position shown in FIGS. land 2 in which exit passagesfor sheet material. At least one of shafts 36 is keyed to the cover toprovide means for pivoting the cover between the open and closedpositions thereof. Support surface 34 is curved and cooperates with thelower or facing surfaces of section 46, when the cover is in theopen-position, to define a convergent passage for guiding the leadingedge of a sheet upwardly into and through the applicator toward thepassage defined by support surface 32 and the facing surface "of edgesection 94.

The applicator is designed to process a succession of sheets,

. each advanced leading edge foremost into the applicator through thepassage defined by support surface'34 and edge section 46. A guide plate48 is provided mounted within the applicator between roll 14 and cover16 for guiding the leading end of the sheet into the passage betweensupport surface 32 =and edge section 44 and supporting the sheet againstthe roll along a line extending full width ofthe sheet duringmovezmentof the sheet'through the applicator.

In the operation of tli'e'applicator apparatus the processing liquid isintroduced into well 18 to maintain the liquid at a static levelslightly above the lowest part of the peripheral surface of the roll. Aconduit'50 leading from the exterior of the applicator through body 12into the'siimp 30 is provided as means for introducing liquid into thewell'fRoll 14 is rotated in a clockwise direction (viewing F lGS.2 and4) so as to entrain and carry the liquid upwardly within the wellbetween the roll quantity of the' pr'ocessing liquid. The presence ofthe meniscus which extends from edge to edge of the sheet insures thatliquid will be applied to all portions of the sheet and that a therewill be no gaps in the liquid coating. w in order to insure formation ofmeniscus 54 andfof eq'ual importance,'application of a predeterminedquantity of the liquid to the sheet commencing at the leading edge ofthe sheet, the surface of roll 14 is textured so as to increase thequantityof liquid entrained by the roll during rotation thereof.

As shown in Fl G. 3, this texturing takes the form of circumferentialgrooves 56 having a generally U-shaped cross section 'anddimensioned tofunction in the nature of capillaries for entraining additional liquid.in a typical applicator structure comprisinga'one irich diameter roll,satisfactory liquid application is achieved with grooves formed as amultiple lead;' 10- pitch thread with a depth of the order of .008 to.010" inch, a jwidth ofl005 to .006 inch, and a land width approximatelythree'times the groove width. The roll is immersed'to a depth ofapproximately three-'sixteenths inch in the liquid within the well andis rotated at a speed such that the surface velocity qf the roll is 2inches per second. Operating with this particular structure and underthe foregoing conditions, a layer of liquid approximately'.0006 inchdeep can be applied to the surface of a sheet moved through theapplicator at the rate of 3 inches per second. r

As previously noted, cylindrical surface 26 is spacedfrom and located inparallel relation with the outer peripheral surface of roll 14andcooperates therewith to provide a throat 27 leading from beneatlifth'eroll upwardly adjacent the ascending side of the roll. Duriitg rotationof roll 14, the liquid within the well tends to rise'within the throatwhichfunctions to limit the level of the liquid'and the quantity thereofwhich is carried on the roll surface beyond the throat and into contactwith the sheet. It has been found that the quantity of liquid availableat meniscus 54 for coating the sheet can be accurately controlled byvarying the depth of throat 28, and in the example given, a depth in therange of .040 inch to .060 inch has proved satisfactory in that itinsures start up of application immediately at the leading edge of asheet contacts the roll,'maintenance of a meniscus 54 of the proper sizeand application of the liquid in a precisely predetermined quantity.Reduction of the depth of the throat will reduce the quantity of liquidavailable forapplication to the sheet while an increase in the depth ofthe throat will result in an increased quantity of liquid up to a pointat which the throat no longer has an effect on the quantity of liquidcarried into contact with the sheet by the roll. Throat 28 serves anadditional function and this is to distribute the liquid on therollsurface more uniformly throughout the length of the 'roll andtogether with meniscus 54 insures against gaps in the layer of liquidapplied to the sheet. The

provision of a throat 27 extending to the lowest part of the roll isimportant because it renders the applicator le'ss level sensitive, thatis, it minimizes the effects of the axis of the roll not being disposedin a horizontal plane. 4

In the operation of the apparatus of the invention to apply a processingliquid to a photosensitive sheet, cover 16 is pivbted to an openposition as the leading edge of the sheet approaches the passage betweencover 16 and side section 26 and rotation of roll 14 is commenced sothat the leading edge of the sheet will meet a wet portion of the rollsurface as the sheet enters the applicator and first contacts the roll.Meniscus 54 forms immediately so at that a continuous layer of liquid ofthe required depth is applied to the sheet throughout the entire lengthof the sheet commencing at its leading edge and rotation of the roll iscontinued until the trailing edge of the sheet has advanced from contactwith the roll whereupon roll rotation is discontinued and the cover ispivoted to its closed position.

It should be noted that the applicator is relatively simple in both itsconstruction and operation, being composed of a minimum of componentsonly two of which move and only one of which comes into contact with theliquid. The applicator may be formed of a variety of materials that arecompatible with the processing liquid and preferably wettable thereby,including metals such as stainless steel and many of the organic plasticmaterials, for example, polypropylene.

Since certain changes may be made in the above apparatus withoutdeparting from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

lclaim:

1. Apparatus for applying an accurately predetermined quantity of aliquid reagent uniformly to a succession of areas of sheet materialcomprising, in combination:

body means defining a well for containing liquid;

a cylindrical roll mounted for rotation about its axis within said well;

means for introducing a liquid reagent into said well beneath said roll;

said well including a wall on one side extending from beneath said rollupwardly to approximately a plane through said axis of said roll;

said wall having a cylindrical surface substantially parallel with andspaced from the peripheral surface of said roll, said surface of saidwall and said roll cooperating to define a throat within which liquidwithin said well is carried upwardly to form a meniscus between saidwall and said roll when said surface of the latter is rotated upwardlywith respect to said wall; and

a cover mounted on said body means for cooperating therewith to define acontainer enclosing said roll and liquid within said well, said coverincluding guide portions and being mounted for movement relative to saidbody means between a closed position in which said guide portions engagesaid support surface to close said container and an open position atwhich said guide portions are spaced from said support surfaces toprovide passages adjacent said sides of said well for guiding sheetmaterial between said body means and said cover across said well incontact with said roll.

2. Apparatus as defined in claim 1 including guide means mounted on saidbody means and located between said roll and said cover for guidingsheet material entering through one of said passages around a portion ofsaid periphery of said roll through said passage on the opposite side ofsaid well.

2. Apparatus as defined in claim 1 including guide means mounted on saidbody means and located between said roll and said cover for guidingsheet material entering through one of said passages around a portion ofsaid periphery of said roll through said passage on the opposite side ofsaid well.